I've invested many years in studying neuroscience and nuclear medicine and many more years in doing research in those fields. When I first started, most of my time was spent with medical journals, but 15 years into my research, much of my time is spent with cookbooks.

These books are essential to contemporary neuroscience because every one of those recipes becomes food, and that food in turn shapes our brains just as surely as it shapes our bodies. It’s a simple and irrefutable premise: The brain receives nourishment strictly through the foods we eat every single day.

Of all the organs in our body, the brain is the one most easily damaged by a poor diet. From its very architecture to its ability to perform, every aspect of the brain calls for proper food. Day after day, the foods we eat are broken down into nutrients, taken up into the bloodstream, and carried up into the brain. Once there, they replenish depleted storage, activate cellular reactions, and finally, become the very fabric of our brains.

Consider that the next time you reach for a brownie: Its ingredients will actually become part of your brain.

And yet I'm surprised by how little attention this receives, both in science and in culture. Especially on the cultural front, the overwhelming majority of best-selling diet books emphasize getting thin or looking young. At best, there are a few popular diets that optimize against coronary conditions or blood sugar or food sensitivity. The brain, it seems, is well-suited to think about most anything except its own well-being.

As the associate director of the Alzheimer’s Prevention Clinic at Weill Cornell Medical College, my work has been focused on the rigorous study of the optimal diet for the brain, not just to prevent or mitigate Alzheimer’s (obvious from the name of our clinic) but also to maintain memory, cognition, and focus over an entire lifetime.

When we eat a fatty, sugary meal and experience symptoms like sluggishness, brain fog, and drowsiness—these symptoms originate not in the stomach but in the brain. More importantly, these aren’t strictly temporary effects. The latest research, including my own work, indicates that a poor diet causes the loss of key structural and functional elements in the brain, with an aggressively higher vulnerability to brain aging and dementia.

By 2050, the United States is well on track to grow from 5 million active Alzheimer’s patients today to 14 million patients needing full-time care (roughly the entire current populations of New York City, Los Angeles, and Chicago put together).

That is a scary statistic, so I'll follow it up with some good news: Recent population-based estimates show that Alzheimer’s could be prevented in at least one of every three potential patients by improving exercise, heart health, intellectual activity, and of course, diet.

Next-generation medical imaging and genomic sequencing have all helped to reveal that some foods are neuroprotective, literally shielding the brain from harm and supporting cognitive fitness over the course of a lifetime. Conversely, other foods and nutrients are downright harmful for the brain, thereby slowing us down in general and deeply increasing the risks of dementia.

As a society, we urgently need to improve our diet in a brain-healthy way. So let me outline and emphasize that there are critical changes that anyone can make, today, to eat right for their brain. Despite what our minds might tell us when presented with a brownie, what our brain actually craves is very specific, carefully selected foods. To get you started, here are three surprising tips for maintaining a brain-healthy diet:

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1. Drink water (a lot of it).

The brain itself is 80 percent water. And every chemical reaction that takes place in the brain, including energy production, needs water to occur. This means that water needs to be replenished on a daily basis. The brain is so sensitive to dehydration that even a minimal loss of water can cause symptoms like brain fog, fatigue, dizziness, confusion (which many of us have experienced in our lives), and more importantly, brain shrinkage (which all of us must do everything to avoid).

Most people don’t yet realize that the water they’re drinking is not optimal for brain health. Purified water, club soda, seltzer—none of these beverages contain the minerals that the brain needs to stay hydrated and work efficiently. The longevity and well-being of both your brain and your body are critically dependent upon consuming hard water. This refers to plain water that is high in minerals and natural electrolytes.

Hard water isn’t hard to find. My personal preference is to drink spring or mineral water. Whether it comes from an underground spring or from an artesian well, spring water is the product of rain and snow filtered through layers of rock, where it picks up all sorts of valuable minerals that are good for you. Likewise, sparkling mineral water that comes from a natural spring also contains various healthful minerals. Carbonation isn’t added by the bottler but from the spring itself. That means that the bubbles in these bottles are completely natural.

In many cities, tap water is perfectly good too—but if you filter it, you may be filtering out some of those essential minerals. If so, take mineral supplements along with your water. Whichever way you get hard water, remember that your brain can’t generate any on its own. Don’t wait until you’re thirsty or exhausted. Train your own brain to keep itself on point.

2. Eat caviar, or eggs and cold-water fatty fish.

At the risk of sounding like brain health is ambitious or expensive to achieve, I have to really recommend caviar. Caviar, and fish eggs at large, contain a unique blend of nutrients that are perfect for brain health: omega-3 DHA fat (a must-have for the brain, most abundant in fish), choline (a B vitamin essential for memory), vitamins B6 and B12 (needed for a strong nervous system), iron (needed for healthy blood), brain-building protein, and even anti-aging vitamins.

It’s not just caviar—of all animal foods available to us, eggs are hard to beat for brain nutrition. That’s because eggs contain so many nutrients that are optimized for a nascent brain to develop. Fish eggs are especially good because these nutrients are combined with an astounding omega-3 DHA load. Caviar can be expensive, of course, so I also strongly recommend cold-water fatty fish like salmon, trout, bluefish, sardines, and anchovies. These are all cheaper and excellent alternatives that are accessible to many more people.

3. Remember that carbs are not the enemy.

If you’ve been in a bookstore or a restaurant lately, you’re well aware of the Great American Gluten Panic. It has led countless people to avoid grains—and subsequently, foods that are rich in carbohydrates and fiber. By all means, patients with Celiac disease (a gluten allergy) and those with gluten sensitivities should continue to avoid gluten. But from a scientific perspective, for the rest of the population there is no conclusive evidence of a connection between gluten consumption and either cognitive decline or dementia. Instead, an absence of fiber has been shown to harm our guts and to therefore affect the population of friendly bacteria in those guts (AKA: the microbiome). Given the established connection between gut health and the brain—a topic all its own—a low-fiber diet may have negative long-term effects on the brain.

If you need more convincing, consider this: A large body of literature on centenarians shows that, all over the world, those who are 100 years old and counting follow high-carb diets. That’s a strong clue that the relationship is a broadly beneficial one. When we study centenarian diets in detail, we note that over 80 percent of calories in their diet comes from vegetables, fruit, legumes, and complex carbohydrates like whole grains, brown rice, oats, and sweet potatoes. These foods are packed with brain-supportive nutrients—from protein to B vitamins to a bounty of antioxidants and minerals. They are also a good source of glucose, the main energy source for the brain. Combined with a high-fiber content to stabilize blood sugar levels, these foods support a healthy digestion and therefore boost the immune system too.

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4. Indulge in dark chocolate.

Chocolate with cacao content of 80 percent or higher is rich in theobromine, a powerful antioxidant known to support cellular aging and reduce the risk of heart disease. Besides, chocolate makes you happy. Try having a small piece of high-quality dark chocolate every day, preferably sugar-free.

In conclusion, the more we learn about what kicks off and accelerates brain aging, the clearer it becomes: It is never too soon to take care of your brain. What we all can do is to take care of the brains we’ve been given, nourishing them thoughtfully, thus naturally extending our chances of a longer, healthier life. For every one of us, our future lies in our own hands and whatever those hands put into our mouths.

Want to learn more about a low-carb diet and the brain? Check this out.